When I try to access the survey (via the link in the invitation email, or after inputing the token), I get the following error (also attached a save of the error I got):

CDbCommand failed to execute the SQL statement: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute

Please open a new issue if this error occurs in some other place. We need to fix all different statements, please attach the full error log like in this report as it really speeds up finding and fixing the erroneous statements.